1. Field of the Invention:
This invention relates generally to a method and apparatus for forming, manipulating and utilizing matter in the plasma state, and more particularly to a method and apparatus for forming, manipulating and utilizing a compound plasma configuration including a toroidal central plasma with electrical current surrounded by a generally ellipsoidal mantle of conducting matter or ionized particles.
2. Description of the Prior Art:
Since the present invention is in the field of high energy plasma physics and is intended to provide a step forward in the search for techniques to maintain controlled thermonuclear reactions, it is believed that a brief discussion of recent developments in the thermonuclear reactor field would be appropriate.
In essence, to achieve nuclear fusion it is necessary to heat a small quantity of fusion fuel above its ignition point, isolate the heated fuel charge from its surroundings long enough so that the release of fusion energy exceeds the input of heat energy, and finally convert the energy released into a useful form. The well known problem that is encountered in attempting to achieve nuclear fusion resides in the fact that relative kinetic energies of 10 KeV or more are required to cause fuel particles to fuse. This energy translates to a 100 million degree kinetic temperature, creating a need for magnetic confinement of the fusion plasma.
The problem that has prevented satisfactory containment of plasmas by magnetic fields is usually related to the inherent instability of the plasma confined in most field configurations and the end losses created by field discontinuities. As a result of the instability and end loss problems, devices existing in the past have been unable to attain a sufficiently high n*tau product to attain fusion. According to the Lawson criterion, the n*tau product must be greater than 10.sup.14 sec per cm.sup.3, implying confinement times of between approximately 0.1 and 1.0 seconds for steady-state reactors. Another view points out that adequate confinement has not been achieved due to the technical limitations related to production of sufficiently high and sustained pressures. The most advanced prior art devices, such as the Tokamak, have been able to attain relatively long confinement times but without adequate pressure to produce the particle densities required at the appropriate temperatures to meet the Lawson criterion. Although laser or "micro-implosion" devices have produced high pressures, the latter are not sustained; consequently, these devices also have failed to achieve time density products anywhere near that required by the Lawson criterion. More extensive analyses of prior art devices and related physics or engineering may be found in the following articles:
Artsimovich, L. A. Tokamak Devices. Nuclear Fusion, 12, 215 (1972). PA0 Bishop, A. Project Sherwood: U.S. Program in Controlled Fusion. Reading, Mass.: Addison Wesley Publishing Company, 1958. PA0 Cobine, J. D. Gaseous Conductors: Theory and Engineering Applications. New York: Dover, 1941, 1958. PA0 Furth, H. P. Tokamak Research. Nuclear Fusion 15, 487 (1975). PA0 Furth, H. P. and S. Yoshikawa. Adiabatic Compression of Tokamak Discharges. Phys of Fluids, 13 2593 (1970). PA0 Glasstone, S. and R. Lovberg. Controlled Thermonuclear Reactions, an Introduction to Theory and Experiment. Princeton, N.J.: D. Van Nostrand Co., 1960. PA0 Gough, W. C. and B. J. Eastlund. The Prospects of Fusion Power. Scientific American, 224, No. 2, 50 (1971). PA0 Kittel, C. Introduction to Solid State Physics. New York: John Wiley, 1971. PA0 Malmberg, J. H. The Pure Electron Plasma, Liquid, and Crystal. Bulletin of the American Physical Society, 22, 9, 1200 (1977). PA0 Post, R. F. Prospects for Fusion Power. Physics Today, 26, Apr., 30 (1973). PA0 Shafranov, V. D. On Magnetohydrodynamical Equilibrium Configurations. J. Exptl. Theoret. Phys., 33, 710 (1957). Translated in Soviet Physics--JETP, 6, 545 (1958). PA0 Tuck, J. L. L'Energie de Fusion. La Recherche, 3, Oct., 857 (1972).
In view of the failure of previously existing systems and techniques to achieve satisfactory confinement of fuel plasmas, and in view of the fact that previous devices have generally consisted of minor variations on a few basic techniques of plasma confinement, it is believed that a need exists for a novel approach to the problems posed by nuclear fusion, and in particular it is believed that a need exists for utilization of a novel plasma configuration. In addition, a brief comparison between this novel plasma configuration and the currently best established approach, a Russian invention the Tokamak, is now made.
The similarity between the magnetic topology of the ATC Tokamak of Princeton's Plasma Physics Laboratory and that of this novel configuration is quite remarkable. Both devices produce a plasma ring with toroidal currents confined by a vertical field. The instant invention also contains poloidal currents in the plasma ring while the Tokamak's poloidal currents are generated in large field coils surrounding a toroidal vacuum chamber. The vacuum chamber wall of the instant invention is a simply connected region and more spherical or ellipsoidal in shape. Hence the name SPHEROMAK was coined by H. P. Furth of Princeton.
The maximum plasma pressure obtainable is on the order of one thousand atmospheres for Tokamaks since they are limited by the stresses on the poloidal field coils. Through pressure leverage the apparatus of the instant invention can achieve a sufficiently sustained pressure on the order of one million atmospheres without exceeding the technological limitations of its confining pressure chamber; consequently its pulsed fusion power density output can exceed that of a Tokamak by over one million times. The compression scaling laws are essentially the same as for the ATC Tokamak (Furth and Yoshikawa, 1970). Unfortunately, tokamaks can be adiabatically compression heated only by a token amount because of the interference of the inner toroidal vacuum wall and large poloidal windings. On the other hand, the method and apparatus of the instant invention can be fully compression heated to the fusion regime after an initial modest ohmic heating warmup period. In its best mode of practice this novel configuration consists of an all Plasma Mantle and Kernel (PLASMAK).